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Disclaimer: At UPMC HealthBeat, we strive to provide the most up-to-date facts in our stories when we publish them. We also make updates to our content as information changes. However, education about COVID-19 can shift quickly based on new data, emerging variants, or other factors. The information in this story was accurate as of its publish date. We also encourage you to visit other reliable websites for updated information, including the Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA), and your state and local governments. 

Updated November 2021

What happens when the annual flu season coincides with the biggest pandemic to hit the world in a century? One possibility that public health experts worry about is a “twindemic.”

What Is a Twindemic?

Twindemic is a new, non-medical term appearing in pop culture when describing the upcoming annual flu season during the COVID-19 pandemic. It describes a particularly severe flu season that occurs alongside a spike in COVID-19 cases. And the nation’s best shot at preventing a twindemic is getting a flu shot.

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Is It Possible to Have the Flu and COVID-19 at the Same Time?

Yes. Flu and COVID-19 are both respiratory illnesses caused by different viruses. That means it’s possible to have the flu and COVID-19 at the same time. It’s also possible to have trouble telling the difference between the two when you begin to have symptoms.

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“Unfortunately, it is possible to get two viruses and these two viruses at the same time if they’re co-circulating,” says Marian Michaels, MD, of the Division of Pediatric Infectious Diseases at UPMC Children’s Hospital of Pittsburgh.

When Is Flu Season?

The flu is a seasonal illness, which means it’s mostly active in the fall and winter. People can get the flu at other times of the year, but it’s unusual. So far, experts don’t have enough experience to know if COVID-19 is seasonal in nature.

COVID-19 vs. Flu Symptoms

Several symptoms are commonly seen in both the flu and COVID-19 are:

  • Fever
  • Dry cough
  • Tiredness

People with COVID-19 also often lose their sense of taste or smell and can become short of breath or have difficulty breathing.

Other symptoms associated with both the flu and less with COVID-19 include:

  • Body aches or muscle pain
  • Headache
  • Loss of appetite
  • Body chills
  • Sore throat
  • Runny or stuffy nose
  • Vomiting or feeling sick to your stomach

“Unfortunately, both COVID-19 and influenza have a lot of overlapping symptoms, so fever, headaches, myalgias, or achy body and joints,” Dr. Michaels says. “Those kinds of things can really be seen with both influenza and COVID-19, so sometimes it’s very difficult to tell without having an actual test.

“There are a couple of things that are a little bit different. With COVID-19, people have seen a new onset of just not being able to smell or taste, and that’s more common with COVID-19 than with influenza. And influenza, in general, comes on a little bit faster and a little bit harder. But to really be able to know, you would have to test to tell the difference.”

Other Differences Between Flu and COVID-19

Medical experts are still learning about core differences between the flu and COVID-19, including about the exact risk of death from COVID-19.

The lowest estimate is that COVID-19 is 6 times deadlier than flu, but other estimates suggest it’s nearly 30 times higher. The risk of dying from both diseases also depends on other factors, especially age and existing medical conditions.

The flu tends to come on quickly and last a shorter time than COVID-19. People with flu experience symptoms within 1 to 4 days of infection and are contagious a day before symptoms appear. The flu can last from a few days to 2 weeks, and longer with complications.

How to Prevent Flu and COVID-19

The good news is there are several things you can do to reduce your risk of COVID-19 and flu at the same time.

The best way to prevent the flu and COVID-19 is to get vaccinated. Americans 5 and older are eligible for the COVID-19 vaccine. The vaccines are safe and effective in preventing COVID-19. They are especially effective in preventing severe illness, hospitalization, and death.

The best way to reduce your risk of flu is to get the flu shot. The flu vaccine usually cuts your risk of catching flu in half each year. And even if you catch the flu, getting the vaccine reduces your chances of serious complications, hospitalization, and death.

Other ways you can reduce your risk of the flu include:

  • Regularly washing your hands, especially before and after touching your face.
  • Using a hand sanitizer containing alcohol if you cannot wash your hands.
  • Trying to avoid touching your eyes, nose, and mouth as much as possible.
  • Wearing a mask or similar face covering in public places and around other people, especially indoors. Mask-wearing in public also is an effective way in lowering your risk of COVID-19.
  • Avoiding close contact with people who are sick.
  • Getting plenty of sleep, eating a healthy diet, exercising regularly, and drinking enough fluids daily.

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Vaccine Effectiveness: How Well Do the Flu Vaccines Work?, National Center for Immunization and Respiratory Diseases (NCIRD), Centers for Disease Control and Prevention. Link

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